This invention relates to a connecting end portion of a planar circuit body, such as a flat cable or a printed circuit body, and the method of manufacturing same.
In general, a planar circuit body, such as a flat cable formed with rectangular conductors (by laminating), and a printed circuit body (formed by printing), each has a connecting end portion which is to be engaged with or connected to a socket or connector.
Examples of known connection end portions of a flat cable are described below.
In one known example, male or female terminals, which are formed by pressing, are fixedly connected to the ends of conductors by welding, thermo-compression bonding, or ultrasonic welding. However, such a connecting end portion tends to be welded or connected insufficiently.
Another example is shown in FIG. 5, in which one side of insulating covers 20 of a conductor 21 is removed so as to partially expose the conductor 21 (as indicated at 22). A reinforcing layer 23 is set under the end portion of the exposed conductor so that the end portion serves as a terminal. When the end portion is inserted into a socket 26 having an elastic terminal 27, the conductor has increased mechanical strength because of the reinforcing layer 23.
FIG. 6 shows another example in which insulating cover 20 of conductors 21 is removed at the ends to expose the conductors 21 (as indicated at 24), and a reinforcing layer 25 of insulating material is set under the exposed conductors 24 (cf. Unexamined Japanese Patent Application Sho. 58-1918 for a more detailed discussion of the terminal connecting sections shown in FIGS. 5 and 6). In the examples shown in FIGS. 5 and 6, the reinforcing layers 23 (FIG. 5) and 25 (FIG. 6) tend to be worn, damaged and/or deformed by the contact load of the mating socket and the elastic terminal 27 of the connector 26. In addition, the contact load decreases over time so that the connecting end portion is liable to provide insufficient contact.
Besides the above examples, a printed circuit body is also known in the art. In order to form a printed circuit body, conductive paste is laid on an insulating film or an insulating covering material, such as film, by screen printing, and then solidified or dried, to form circuit conductors (circuit patterns). Examples of the printed circuit body are described below.
The end portions of the circuit conductors are brought into contact with an electronic component or components. However, this suffers from the problems that the connecting end portion tends to have a high electrical resistance.
In another example, the end portions of the circuit conductors are connected to an electronic component or components by soldering. This is problematic because it is not applicable to a film substrate which has a low melting point.
In yet another example, a special connector is employed. This example is problematic because it is difficult to apply the connecting end portion to a printed circuit body for high power because heat is generated. In a printed circuit, a circuit pattern is formed by printing, and after being solidified, it is subjected to copper plating until generally the conductor thickness reaches the square of the wire diameter.
In addition to the problems mentioned above for the various examples, in each of these examples, the connecting end portion requires a welding or soldering step, which increases the number of required manufacturing steps, thereby lowering work efficiency.